The present invention broadly relates to a new and improved apparatus for recoilless firing of projectiles from a launching tube or firing barrel.
In its more specific aspects, the present invention relates to a new and improved apparatus for recoilless firing of projectiles from a launching tube or firing barrel, comprising a forward brake or retaining ring, a forward piston or sabot, a propellant charge with a firing or ignition screw, a rear piston or sabot, a counter-mass and a rear brake or retaining ring.
An apparatus of this general type has already been described in the German Patent Publication No. 2,140,875, wherein there is arranged a propellant charge between two pistons or sabots, causing the two pistons within the launching tube to be displaced in respective forward and rearward directions upon ignition of the propellant charge. A first one of the pistons transports the projectile forwardly to exit from the launching tube. This first piston strikes against the forward brake ring and the second piston pushes the counter-mass until it protrudes from the rear end of the weapon barrel or launching tube when this second piston strikes the rear brake ring.
For recoilless operation it is essential that the weight of the projectile and the weight of the counter-mass be arranged in a predetermined mutual relationship. Furthermore, the path traveled by the forward piston as well as the path traveled by the rearward piston, for expulsion of the projectile and thrusting of the counter-mass, must also be arranged in a predetermined mutual relationship in order to avoid any recoil effects. In order to prevent propellant gases from leaving the launching tube, the two pistons are retained at each end of the launching tube by the brake rings, such that the launching tube remains sealed. Flame and smoke generation as well as firing noise can thus be avoided, which is necessary to avoid revealing the position of the launching tube to the enemy or for permitting firing of the projectile from an enclosed space.
The acceleration paths of the pistons are limited in accordance with the length of the launching tube. In order to nevertheless obtain a high muzzle velocity of the projectile, a high pressure of the propellant gases is required. In order to avoid damage to the launching tube, to the pistons and to the projectile by these high pressures, a suitable, robust construction of these elements is necessary, causing the weapon to become heavy and no longer transportable by an individual artilleryman.
In order to avoid excessive pressures, extensible or telescoping launching tubes of this general type have already been disclosed (see German Patent Publication No. 3,102,734, published Aug. 5, 9182). The apparatus, when in primed condition, includes an arrangement comprising an internal tube located between the propellant charge and the rear end of the launching tube. The internal tube contains a rear sabot, an ejectable inertial mass, as well as a rear brake ring. The internal tube is telescopically moveable out of the launching tube. This interal tube comprises a stop arrangement at its internal termination and which strikes against a stop arrangement at the rear termination of the launching tube.
Arrangements for avoiding high pressures are also known in the art. Reference is made to the European published Patent Application No. 0,056,789. This European published patent application describes an installation for recoilless firing of a rocket, comprising at least one launching tube and at least one projectile for each launching tube. The launching tube comprises at least one chamber for receiving a stationary propellant charge. The rocket projectile possesses at least one propellant charge for sustaining the launching speed or muzzle velocity and for elimination of side wind effects. One embodiment exhibits two stationary propellant charges and two propellant charges within the projectile.
Furthermore, there is known to the art a certain type of warhead with adjustable propellant charge for different firing ranges (see German Patent Publication 2,752,844, published Aug. 19, 1982). This warhead may be fired from a nozzle cannon without recoil effect. The propellant charge is subdivided such that a portion of, or the entire propellant charge can be ignited as desired. A certain portion of the propellant charge is fastened to the warhead and a certain portion of the propellant charge is located in a compartment of the nozzle cannon. The propellant compartment of the nozzle cannon is arranged in an annular configuration around the nozzle barrel of the nozzle cannon, while the outside wall is constructed in a pressure-resistant configuration. The inside wall for the section containing the propellant charge is of a permeable configuration.
The known arrangements for recoilless firing of projectiles from a launching tube are afflicted with high peak pressure effects, despite telescoping-type internal tubes for extension of the acceleration path and despite multi-stage configurations, since propellant charges are used which have gas pressure characteristics similar to propellant charges used for artillery. Upon igniting a propellant charge, the developing gases generate a pressure peak within the combustion chamber which still further increases as soon as the projectile starts moving.
As soon as the combustion chamber starts to increase in size at an increasing rate, caused by the displacement of the projectile, the pressure starts to diminish again. In accordance with the behavior of the propellant charge powder and in accordance with the acceleration of the projectile, as well as a thus effected expansion of the combustion chamber, the gas pressure is reduced at a higher or lower rate. The higher the peak pressure, the higher is the initial acceleration of the projectile, thus requiring a robust construction of the projectile. With multi-stage arrangements only a rapid decrease of pressure within the combustion chamber can be avoided--however, the disadvantageous high pressure peak cannot be eliminated.